Thermostats



June 2, 1959 v w. D. SMITH 2,389,430

- THERMOSTATS Filed Jan. 11, 1957 FIG. 2.

XEQZ/G ma 15550 United States atent THERMOSTATS Webster Deroyce Smith, Palos Verdes Estates, Calif.

Application January 11, 1957, Serial No. 633,576

'Claims. (Cl. 200-438) My invention relates to thermostats and particularly to those to be used as control devices in switching electrical circuits.

Some advantages of my improved thermostat are: it is insensitive to vibration and impact; it operates to close temperature tolerances; it is compact and light weight; and it may be hermetically sealed to prevent environmental contamination.

These and other objects of my invention will appear as the description proceeds.

In the drawings: Figure l is a sectional view through the axis of the cylindrical body member. Figure 2 is a sectional view through the plane X-X.

Through its center, bimetallic disc 1 is attached to body member 2 by temperature adjusting screw 3 which holds disc initially in contact with sharp ring 4. Electrical insulating and hermetic sealing element 5 is secured in opposite end of body and supports contact pins 6, 7, and 8, and actuator support pin 9. Spring contact element is secured to pin 6 and presses against pin 7 initially. Insulating actuator member 11, slidably supported by pin 9, is initially constrained from motion by ledge 12 of body member and loop in element 10.

In operation the device functions as follows: at the pre-adjusted temperature, thermal disc 1 snaps over center such that its periphery drives actuator 11 against loop in element 10 which serves as its own fulcrum where it crosses over itself and therefore jumps over pin 7 to contact pin 8 as shown by phantom lines. Pins 6, 7, and 8 thus serve as a spring loaded single pole double throw switch which actuates at a predetermined temperature. The ring 4 is of the proper radius to dynamically balance disc 1 against sensitivity to vibration, impact or acceleration. It is to be pointed out that the elements are so spaced that the disc is not loaded by touching actuator 11 until after it snaps over center. It is emphasized that such a mounting for a thermal element is unique and may be used to trigger or actuate many devices other than switches. It is also to be noted that a compression spring, although not shown, may be inserted under the head of screw 3 to press disc 1 more securely against ring 4. Provision of an actuating member that is concentric with the head of screw 3 may also be made,

ice

such that the motion of the center instead of the periphery of the disc can be used for actuation.

Although variations of my arrangement of elements may be made, and details may be changed, the foregoing nevertheless explains the elements and spirit of my invention.

1 claim:

1. Switch means comprising an elongate resilient member formed in a loop, means fixing one end of said member, the other end of said member being left free, the cross-over point of said loop constituting a fulcrum for pivoting of the free end of said member, a pin disposed adjacent said free end, said free end being anchored behind said pin, such anchorage stressing said resilient member, and an actuating mem'ber engaging said loop at a point spaced from said cross-over point to pivot said free end about said fulcrum, thereby to free it from said pin and enable it to snap away from said pin by the resiliency of said resilient member.

2. Switch means in accordance with claim 1, including a thermally actuated snap member disposed adjacent the other end of said actuating member, in position to actuate the same and thereby pivot said resilient member upon snapping of said snap member.

3. Thermal actuated apparatus comprising a thin cambered thermally actuated snap member, means for sup porting said member spaced from the center thereof, means for setting the camber of said snap member, thereby to control the temperature at which said member snaps, said supporting means being spaced from said center so as to constitute means for dynamically balancing said snap member, said supporting means comprising an annular ridge spaced between the periphery and center of said snap member, and said actuated member being spaced radially outward from said ridge.

4. Apparatus in accordance with claim 3, including an annular shoulder against which said actuated member rests and serving to separate said actuated member from said snap member until thermal snapping of said snap member is eifected.

5. Thermal actuated apparatus comprising a thin cam- *bered thermally actuated snap member, means for supporting said member spaced from the center thereof, and an actuated member spaced from said supporting means in position to be moved upon snapping of said snap member, said supporting means comprising an annular ridge against which said snap member bears.

References Cited in the file of this patent UNITED STATES PATENTS 1,823,345 Britt Sept. 15, 1931 1,952,895 Ross Mar. 27, 1934 2,596,171 Rabinow May 13, 1952 2,714,644 Harrison Aug. 2, 1955 2,732,461 Huber Ian. 24, 1956 2,752,454 Kurtz June 26, 1956 2,753,421 Mertler July 3, 1956 

